1. Field of the Invention
The invention relates to integrated circuits, and more particularly to integrated circuits which convert a digital signal to an analog signal.
2. Description of the Related Art
As semiconductor manufacturing technology is rapidly progressing, it is possible to integrate analog and digital circuitry, which was previously implemented on a conventional board, on a single chip. Therefore, digital-to-analog converters (DACs), the interface between digital and analog systems, are regarded as key components in accomplishing integrated system design.
Digital-to-analog conversion refers to the process of converting discrete digital signals into a continuous-time range of analog signals. The trend in DACs is toward higher speeds and higher resolutions at reduced power levels. However, DACs tend to have relatively poor dynamic performance as they operate with high update rates. This is because the dynamic performance of a DAC is adversely affected by a “glitch”. Transient voltages may appear at the DAC output due to the periodic code updates applied to the DAC. More succinctly, input code transitions for DACs frequently incur a glitch in the analog output. Glitches obscure the generation of the analog output representing the digital input code. This problem becomes pronounced particularly when the DACs operate at high frequencies. It is desirable to provide a DAC having significant reduction in the glitch. Furthermore, DACs employed in modern communications applications preferably offer the ability to control the common-mode voltage appearing on differential outputs. There is a need to provide a differential voltage output DAC, addressing the above-described requirements.